chore(golangci-lint): improve and clean configuration

[ldez]

• I have read and followed the Contribution Guide

A small improvement to your configuration file.

gofmt is redundant with gofumpt.
rewrite-rules can be replaced with modernize.

There is no need to instruct all the formatters with the import group, gci already handles it.

I guess the options inside the exclusion section (paths and generated) have been created during the v1 to v2 migration, those elements was here only for some edge case compatibilities with the v1, but you don't need them.

[andreynering]

This is great, thank you!